JPH0736051U - Gas analyzer - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a gas analyzer in which light emitted from a light source is applied to a cell as a high-density parallel light beam and is made incident on a detector in that state. A gas analyzer in which a light source unit 1, a cell 8 and a photodetector 14 are arranged in series in this order is provided.
Has a spheroidal space 3 formed inside a block body 2 and a light source 5 provided at a first focus position 6 thereof. A convex lens body 9 is provided between the light source unit 1 and the cell 8. The focal point 11 is arranged so as to match the second focal point position 7 in the spheroidal internal space.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a gas analyzer for injecting infrared rays or ultraviolet rays into a cell to analyze components contained in a sample gas.

[0002]

[Prior art]

 In the gas analyzer, generally, the larger the amount of light incident from the light source on the cell to which the sample gas is supplied, the higher the detection sensitivity, and the analysis is performed with high accuracy. Therefore, conventionally, as shown in FIG. 3, the amount of light incident on the cell and the photodetector is increased to increase the detection sensitivity.

That is, FIGS. 3A to 3C each show a conventional infrared gas analyzer. First, in FIG. 3A, 31 is a metal such as stainless steel to which the sample gas S is supplied. It is a cylindrical cell made of, and its inner surface is mirror-finished. Reference numerals 32 and 33 are cell windows for closing both ends of the cell 21, and 34 and 35 are inlets and outlets for the sample gas S.

Reference numeral 36 denotes a light source section which is arranged so as to face one cell window 32. A conical opening 38 is formed in a block body 37 made of a metal such as aluminum, and a wall surface surrounding the opening 38 is reflected. The surface 39 is formed, and the infrared light source 40 is arranged on the apex side of the conical opening 38.

Reference numeral 41 is a photodetector composed of a solid-state detector provided opposite to the other cell window 33, and 42 is an optical filter arranged in front of the photodetector 41, for example, passing light in a specific wavelength range. A multilayer interference filter 43, a rotary chopper 43 provided between the optical filter 42 and the cell window 33, a motor 44 for driving the rotary chopper 43, and a preamplifier 45.

Further, in the infrared gas analyzer shown in FIG. 3B, as the light source section 46, a metal parabolic body 37 is provided with a reflecting surface 47 having a paraboloid of revolution, and other configurations are as follows. This is the same as that shown in FIG.

In the infrared gas analyzer shown in FIG. 3C, a spheroidal space 49 is formed in the metal block 37 as the light source unit 48, and a wall surface 50 having an elliptical cross section is reflected. In addition to being a surface, the infrared light source 40 is arranged at one focus position 51 of the elliptical space 3, and the other focus 52 of the elliptical space 3 is located slightly inside the cell window 33.

[0008]

[Problems to be solved by the device]

 In the infrared gas analyzer shown in FIGS. 3 (A) and 3 (B), the light emitted from the infrared light source 40 is, as indicated by an arrow in the figure, a light beam (parallel to the effective length direction of the cell 31). Hereinafter, it will be referred to as parallel rays, and will pass through the cell 31 and enter the photodetector 41. In addition, in the infrared gas analyzer shown in FIG. 3C, in addition to the parallel rays, as shown in the figure, light traveling while reflecting inside the cell 31 enters the photodetector 41, The amount of light passing through and the amount of light reaching the photodetector 41 increases.

However, in the infrared gas analyzer shown in FIGS. 3 (A) and 3 (B), the diameters of the reflecting surfaces 39 and 47 are large due to the filament size of the light source 40. Since the diameter of 31 is inevitably large, the replacement speed of the sample gas S is slow, and there is a drawback that the response is lacking accordingly. Further, when the photodetector 41 having a small light receiving part such as a pyrosensor is used, the incident light density becomes low, and thus a large detector output cannot be obtained.

In the infrared gas analyzer shown in FIG. 3C, the light is attenuated due to the reflection of the light in the cell 31, and the light not incident on the photodetector 41 increases. Further, in the case where the optical filter 42 is provided, the ratio of light incident from an oblique direction with respect to this increases, so that the light transmitted through the optical filter 42 shifts to the short wavelength side and the bandpass filter In the case of, there is a problem that the transmission band is widened and the error increases accordingly.

The present invention has been made in consideration of the above matters, and a gas analyzer which irradiates light emitted from a light source as high-density parallel rays onto a cell and makes the cell enter a detector in that state. Is intended to provide.

[0012]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a gas analyzer in which a light source section, a cell, and a photodetector are arranged in series in this order, wherein the light source section has a spheroidal space inside a block body. Is formed and a light source is provided at the first focal point position, and a convex lens body is provided between the light source section and the cell in a state where the focal point thereof coincides with the second focal point position of the spheroid internal space. It is arranged.

[0013]

[Action]

 In the gas analyzer with the above configuration, since the light source is located at one of the focal points of the inner space of the spheroid, all the light emitted from the light source that is reflected by the reflecting surface of the block body is inside the spheroid. Focus on the other focus of space. Since the other focal point is also the focal point of the convex lens body provided between the light source and the cell, the light collected at the other focal point becomes all parallel rays after passing through the convex lens body. Then, this normal ray passes through the cell and is incident on the photodetector.

That is, in the gas analyzer having the above-mentioned configuration, most of the light emitted from the light source can be applied to the cell as parallel rays and made incident on the photodetector in the parallel state. The power output can be increased. Further, since the ratio of parallel rays is increased, the diameter of the cell can be reduced, and therefore the replacement speed of the sample gas can be increased, so that the responsiveness is improved. Further, when the optical filter is provided on the front surface side of the photodetector, the wavelength of the light transmitted through the optical filter does not shift, and therefore the error can be reduced.

[0015]

【Example】

 FIG. 1 shows an example of an infrared gas analyzer to which the present invention is applied, showing a so-called single beam / single cell type infrared gas analyzer. In FIG. 1, reference numeral 1 denotes a light source portion, and a spheroidal space 3 is formed inside a block body 2 made of a metal such as aluminum. One side of the space 3 is open, and a wall surface (reflection surface) 4 surrounding the space 3 has an elliptical cross-sectional shape and is mirror-finished. An infrared light source 5 is located at one focus position (first focus) 6 of the elliptical space 3. Reference numeral 7 denotes the other focus position (second focus) of the elliptical space 3.

Reference numeral 8 denotes a cylindrical cell made of, for example, stainless steel, which is provided on the opening side of the light source block body 2. The inner wall of the cylindrical cell is mirror-finished, and both ends of the cell window 9 are made of an infrared transmitting material. It is closed by 10. The cell window 9 near the light source block body 2 is formed in a convex lens shape, and its focal point 11 is set to coincide with the second focal point 7 of the elliptical space 3. That is, in this embodiment, the cell window 9 also serves as the convex lens body. The other cell window 10 is the same as in a conventional gas analyzer of this type. Further, 12 and 13 are inlets and outlets of the sample gas S 2.

Reference numeral 14 is a photodetector provided so as to face the cell window 10, and is composed of a solid-state detector such as a pyrosensor, a thermopile sensor, or a semiconductor sensor. Reference numeral 15 denotes an optical filter arranged on the front surface of the photodetector 14, which is, for example, a multilayer interference filter that allows light in a specific wavelength range to pass therethrough. Reference numeral 16 is a rotary chopper provided between the optical filter 15 and the cell window 10, 17 is a motor for driving the rotary chopper 16, and 18 is a preamplifier whose output is input to a signal processing unit (not shown).

In the infrared gas analyzer configured as described above, since the infrared light source 5 is provided at the first focus 6 of the spheroidal internal space 3 formed in the light source block body 2, Of the light emitted from the external light source 5, all the light reflected by the reflecting surface 4 surrounding the spheroidal internal space 3 is collected at the second focus 7 of the spheroidal internal space 3. The second focal point 7 is also the focal point of the convex lens body 9 provided on the light source side of the cell 8, so that the light collected at the second focal point 7 is all parallel after passing through the convex lens body 9. It becomes a ray. Then, the parallel rays pass through the cell 8 and then enter the photodetector 14 through the other cell window 10 and the optical filter 15.

That is, in the gas analyzer having the above-described configuration, most of the light emitted from the infrared light source 5 can be applied to the cell 8 as parallel rays, and can be incident on the photodetector 14 in the parallel state. , The detector output can be increased accordingly. Further, since the ratio of parallel rays is increased, the diameter of the cell 8 can be reduced, and therefore the replacement speed of the sample gas can be increased, so that the responsiveness is improved. In addition, since the light passing through the cell 8 enters perpendicularly to the incident surface of the optical filter 15 and is transmitted toward the photodetector 14 in that state, there is no wavelength shift in the transmitted light. The error is reduced.

In the above-described embodiment, since the convex lens body 9 also serves as the cell window, the number of parts is small and the entire apparatus can be made compact.

FIG. 2 shows another example of an infrared gas analyzer to which the present invention is applied. In this embodiment, the cell window 19 on the light source side of the cell 8 is configured similarly to the other cell window 10, and the convex lens body 20 is provided on the opening side of the spheroidal internal space 3 of the light source block body 2. . In this case, it goes without saying that the convex lens body 20 is provided so that its focal point 11 coincides with the second focal point of the spheroidal internal space 3. The operation of the infrared gas analyzer configured as described above is the same as that of FIG. 1, and thus the description of the device is omitted.

The present invention is not limited to the above-described embodiment, and for example, the optical filter 15 does not necessarily have to be provided. Further, the rotary chopper 16 may be provided between the light source block 2 and the cell 8. Further, it can be applied to a so-called fluid modulation type infrared gas analyzer in which the sample gas and the reference gas are alternately introduced at a constant cycle, and in that case, the rotary chopper 16 is unnecessary. Furthermore, the present invention can be similarly applied to an ultraviolet gas analyzer using an ultraviolet light source instead of the infrared light source 5.

[0023]

[Effect of device]

 As described above, according to the present invention, compared with the conventional gas analyzer, most of the light emitted from the light source can be radiated to the cell as parallel rays and made incident on the photodetector in the parallel state. Since it is possible, the detector output can be increased correspondingly, and highly accurate measurement is possible. Further, since the ratio of parallel rays is increased, the diameter of the cell can be reduced, and therefore the replacement speed of the sample gas can be increased, so that the responsiveness is improved. Further, when the optical filter is provided on the front side of the photodetector, the wavelength of the light transmitted through the optical filter does not shift, and therefore the error can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a gas analyzer according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a gas analyzer according to another embodiment of the present invention.

FIG. 3 is a diagram showing a conventional gas analyzer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source part, 2 ... Block body, 3 ... spheroidal internal space, 5 ... Light source, 6, 7 ... Focus of spheroidal internal space, 8
... cells, 9, 20 ... Convex lens body, 11 ... Focus of convex lens body, 14 ... Photodetector.

Claims (1)

[Scope of utility model registration request] 1. A gas analyzer in which a light source section, a cell, and a photodetector are arranged in series in this order, wherein the light source section has a spheroidal space formed inside a block body. A light source is provided at a focal position, and a convex lens body is arranged between the light source portion and the cell in a state where the focal point of the convex lens body coincides with the second focal position of the spheroidal internal space. Gas analyzer.